The report warns that oceans are “at high risk of entering a phase of extinction of marine species unprecedented in human history,” due to well documented threats including over-fishing, climate change, pollution and hypoxia.

The experts noted the speed of the seas’ decline and the unfortunately self-reinforcing effects of the challenges marine animals face.

“What we’re seeing at the moment is unprecedented in the fossil record – the environmental changes are much more rapid,” said Alex Rogers, IPSO’s scientific director and professor of conservation biology at Oxford University.

Not only have previous mass extinction events been linked in the fossil record to the same problems now facing the oceans — on which all life on the planet ultimately depends — but the levels of carbon dioxide being absorbed by the oceans are already far higher than during a wipeout of marine species 55 million years ago.

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Another recent study found that the Atlantic coast of the United States has just undergone the fastest sea-level rise in two millennia, thanks to rising temperatures.)

To have a chance of preserving the seas as we know them, one study author said, we will have to bring carbon emissions to zero within 20 years.